Modern gas turbines may operate on a number of different fuels, such as various kinds of liquid and gaseous fuels. For this reason, power plants may have gas turbine engines that can operate with dual fuel capability, for example, natural gas and diesel fuel. In general, the choice of operational fuel depends on the price, availability and operational parameters.
Gas turbines comprise various types of combustors configured to produce a hot gas by burning a fuel in a compressed air. The fuel is introduced in the combustor using one or more fuel nozzles. To provide an operational flexibility, the nozzles usually have capabilities to inject a dual fuel.
Dual fuel has to be delivered to the fuel nozzles from the fuel source. Design of such dual fuel delivery systems has various challenges such as: space constrains, vibrational instabilities and thermal expansions.
FIG. 2 shows a fuel delivery system 200 comprising two fuel ring pipes, 202 and 204. Each of the ring pipes, 202 and 204, supplies one type of the fuel, and each pipe has plurality of fuel feeds 206 which are connected to combustor burners (not shown) of a gas turbine. In the configuration where every burner has one lance, one branch from each of the ring pipes 202 and 204 supplies two types of the fuel to the single burner. This design results in the high level of complexity and high number of supply lines and connections. FIG. 3 shows dual fuel supply system 300 for a burner 312 having several (in this example three) injection nozzles 310. Two types of fuel, 302 and 304, are supplied to every nozzle 310. Fuel 302 is supplied via a first fuel line 306, while second fuel 304 is supplied via a second fuel line 308. Similarly to the design from FIG. 2, this fuel delivery system is not compact and it could suffer from thermal and vibrational instabilities.
What is desired, therefore, is dual fuel delivery system that is simpler and more efficient than the systems from the prior art.